An electrical connector assembly which is designed with intermatable connector halves for high- speed signal transmission is well known in the art. In this type of electrical connector, a plug connector half is designed with a plurality of plug contacts which are aligned on a convex feature provided in a housing while a receptacle connector half is designed with a plurality of receptacle contacts which are aligned on a concave feature provided in another housing. These plug and receptacle connectors are electrically connected to enable signal transmission when their respective housings are mated by inserting the convex portion of the plug connector into the concave portion of the receptacle connector and thereby the interconnecting corresponding pairs of plug and receptacle contacts. In this type of high-speed signal transmission connector, these electrical contacts are usually positioned with a relatively small pitch in the respective housings, so signal leak (i.e., crosstalk) between adjacent contacts is likely to happen. In addition, if there is a mismatch of impedance, then signal reflection is likely to occur. To prevent such problems, various methods are proposed.
One method is to provide a grounding plate in parallel with the rows of plug contacts which are aligned on opposites sides of the convex portion of the plug connector or in parallel with the rows of receptacle contacts which are aligned in the housing of the receptacle connector and to connect this grounding plate to a grounding pathway provided on a printed circuit board by using a special part.
However, in this method, the special part is designed especially for this grounding connection, so the provision of this special part increases the number of parts necessary for the production of the electrical connector, which is disadvantageous in reducing production cost. Beside this disadvantage, the existence of this special part, which is used solely for the electrical grounding of the electrical connector, creates an unwanted impedance characteristic. Moreover, a relatively long electrical pathway is required for connecting this special grounding part, which is provided in the electrical connector, to a grounding pathway which is provided on the printed circuit board. This long electrical pathway is a hindrance to any attempt which can be effected to improve the impedance characteristic of the electrical connector.